Im creating a window class in C++ to provide a bit of abstraction for a GLFW window.

The code works as intended. Im really new to c++ tho and I assume there is tons i could improve about this class, not just in terms of speed, but also structure.

Im especially concerned with the way I get around the fact that GLFW callbacks are static. In my callbacks I want to acces methods in my class and so I create a pointer to the actual 'window user' using glfwGetWindowUserPointer, to acces the actual class methods an member variables.

Still i'm just looking for any thought on how to improve this code.

I'm creating a window class in C++ to provide a bit of abstraction for a GLFW window.

The code works as intended. I'm really new to c++ though and I assume there are tons I could improve about this class, not just in terms of speed, but also structure.

I'm especially concerned with the way I get around the fact that GLFW callbacks are static. In my callbacks I want to access methods in my class and so I create a pointer to the actual 'window user' using glfwGetWindowUserPointer, to access the actual class methods an member variables.

Still I'm just looking for any thoughts on how to improve this code.

Im creating a window class in C++ to provide a bit of abstraction for a GLFW window. To me it makes sense to add a key_callback as a method in my class. The issue is ofcourse that GLFW is written in C, and so it requires callbacks to be static.

I found that GLFW has a glfwSetWindowUserPointer function that sets:

.. sets the user-defined pointer of the specified window.. ----- Docs

So I went with the following solution:

In my window.h:

class Window {
    GLFWwindow* window;
    // More members..
    
public:
    Window(...); // Constructor

private:
    // Stuff...

    void setKeyCallback(); // Function to set keycallback
    static void static_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods); // The static keycallback
    void keyCallback(int key, int scancode, int action, int mods); // Non static keycallback
};

In my window.cpp:

Window::Window(...) {
    glfwSetWindowUserPointer(window, this);
    setKeyCallback();
    // more stuff
}

void Window::setKeyCallback() {
    glfwSetKeyCallback(window, static_KeyCallback); // Set keycallback to static member function
}

void Window::static_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods) {
    Window* actualWindow = (Window*) glfwGetWindowUserPointer(window); // Get a pointer to the window instance that has the actual window.
    actualWindow->keyCallback(key, scancode, action, mods); // Acces that actual window instanceses method
}

void Window::keyCallback(int key, int scancode, int action, int mods) {
    // Do stuff..
}

The primary reason that I need(or would like) the callback to be nonstatic is because I want to use methods from the Window class inside the callback.

Clearly there is some overhead in having to retrive a pointer to the actual instance everytime a button is pressed, so my question is, would you consider this an optimal solution?

Im creating a window class in C++ to provide a bit of abstraction for a GLFW window.

window.h

#pragma once

#define GLFW_INCLUDE_VULKAN
#include <GLFW/glfw3.h>

class Window {
    GLFWwindow* m_Window;
    GLFWmonitor* m_Monitor;

    const char* m_Title;
    GLFWimage m_Icon[1];
    int m_Width, m_Height;
    int m_PosX, m_PosY;
    bool m_Fullscreen;

public:
    Window(int width, int height, const char* title, const char* iconPath); 
    ~Window();

    GLFWwindow* getWindow();

    const char** getRequiredExtensions();

private:
    void queryVulkanSupport();

    void initGLFW(); 
    void createWindow();

    void setIcon(const char* path);
    void center();
    void setFullscreen();

    void setWindowSizeCallback();
    static void static_WindowSizeCallback(GLFWwindow* window, int width, int height);
    void windowSizeCallback(int width, int height); 

    void setKeyCallback();
    static void static_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods); 
    void keyCallback(int key, int scancode, int action, int mods);
};

window.cpp

#include "window.h"

#define STB_IMAGE_IMPLEMENTATION
#include <stb/stb_image.h>

#include <stdexcept>
#include <string>

Window::Window(int width, int height, const char* title, const char* iconPath)
    : m_Fullscreen(false), m_Width(width), m_Height(height), m_Title(title) {
    initGLFW();
    queryVulkanSupport();
    m_Monitor = glfwGetPrimaryMonitor();
    createWindow();
    setIcon(iconPath);
    setWindowSizeCallback();
    setKeyCallback();
}

Window::~Window() {
    glfwDestroyWindow(m_Window);
    glfwTerminate();
}

GLFWwindow* Window::getWindow() {
    return m_Window;
}

const char** Window::getRequiredExtensions()
{
    uint32_t count;
    const char** extensions = glfwGetRequiredInstanceExtensions(&count);
    return extensions;
}

void Window::queryVulkanSupport() {
    if (!glfwVulkanSupported()) {
        throw std::runtime_error("Vulkan not supported!");
    }
}

void Window::initGLFW() {
    if (!glfwInit()) {
        throw std::runtime_error("Failed to initialize GLFW!");
    }
}

void Window::createWindow() {
    glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
    m_Window = glfwCreateWindow(m_Width, m_Height, m_Title, nullptr, nullptr);
    if (!m_Window) {
        throw std::runtime_error("Could not create GLFW window!");
    }
    glfwSetWindowUserPointer(m_Window, this); 
    center();
}

void Window::setIcon(const char* path) {
    m_Icon[0].pixels = stbi_load(path, &m_Icon[0].width, &m_Icon[0].height, 0, 4);
    if (m_Icon[0].pixels)
        glfwSetWindowIcon(m_Window, 1, m_Icon);
}

void Window::center() {
    const GLFWvidmode* vidMode = glfwGetVideoMode(m_Monitor);
    glfwSetWindowPos(m_Window, (vidMode->width - m_Width) / 2, (vidMode->height - m_Height) / 2);
}

void Window::setFullscreen() {
    if (!m_Fullscreen) {
        const GLFWvidmode* vidMode = glfwGetVideoMode(m_Monitor);
        glfwGetWindowPos(m_Window, &m_PosX, &m_PosY);
        glfwGetWindowSize(m_Window, &m_Width, &m_Height);
        glfwSetWindowMonitor(m_Window, m_Monitor, 0, 0, vidMode->width, vidMode->height, vidMode->refreshRate);
        glfwSetWindowSize(m_Window, vidMode->width, vidMode->height);
        m_Fullscreen = !m_Fullscreen;
    }
    else {
        glfwSetWindowMonitor(m_Window, nullptr, m_PosX, m_PosY, m_Width, m_Height, 0);
        glfwSetWindowSize(m_Window, m_Width, m_Height);
        m_Fullscreen = !m_Fullscreen;
    }
}

void Window::setWindowSizeCallback() {
    glfwSetWindowSizeCallback(m_Window, static_WindowSizeCallback);
}

void Window::static_WindowSizeCallback(GLFWwindow* window, int width, int height) {
    Window* actualWindow = (Window*) glfwGetWindowUserPointer(window); 
    actualWindow->windowSizeCallback(width, height);
}

void Window::windowSizeCallback(int width, int height) {
    glfwSetWindowSize(m_Window, width, height);
}

void Window::setKeyCallback() {
    glfwSetKeyCallback(m_Window, static_KeyCallback);
}

void Window::static_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods) {
    Window* actualWindow = (Window*) glfwGetWindowUserPointer(window);
    actualWindow->keyCallback(key, scancode, action, mods);
}

void Window::keyCallback(int key, int scancode, int action, int mods) {
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(m_Window, true);
    if (key == GLFW_KEY_F11 && action == GLFW_RELEASE)
        setFullscreen();
}

main.cpp

#include "window.h"

int main() {
    Window window(600, 300, "Vulkan engine!", "include/Ressources/VulkanIcon.png");

    while (!glfwWindowShouldClose(window.getWindow())) {
        glfwPollEvents();
    }
}

The code works as intended. Im really new to c++ tho and I assume there is tons i could improve about this class, not just in terms of speed, but also structure.

Im especially concerned with the way I get around the fact that GLFW callbacks are static. In my callbacks I want to acces methods in my class and so I create a pointer to the actual 'window user' using glfwGetWindowUserPointer, to acces the actual class methods an member variables.

Still i'm just looking for any thought on how to improve this code.

Links to GLFW and STB.